1. Field of the Art
This invention relates to a process for hydrating a nitrile compound by the action of microorganisms having nitrilase activity to convert the nitrile compound into the corresponding amide compound. More particularly, this invention relates to the process for producing an amide compound by (irradiation with light of the microorganisms) with good yield, space time yield and productivity per bacterial cells (i.e. the amount of amide compounds to be produced per unit amount of bacterial cells used).
Recently there have been developed processes for carrying out chemical reactions by the use of microorganisms or enzymes obtained therefrom. In general, the reactions by means of microorganisms or enzymes are advantageous in that consumption of energy for the reactions is small because the reaction can be carried out at room temperature and atmospheric pressure and that desired products of high purity are easily obtained because the selectivity of the reaction to yield the desired products is very high. On the other hand, there is room for improvement with respect to the reaction activity, the life time of microorganisms or enzymes used as catalysts. Especially, there are problems when the velocity of the desired reaction (i.e. reaction activity) is low under its optimum conditions and especially at its optimum temperature and/or pH. In such a case, the productivity per bacterial cells used is reduced because large capacity reactors are required owing to low space yield, the reaction takes a longer time owing to a slow reaction velocity, and also the reaction activity is lowered.
Thus, it is fundamentally important to realize a high reaction activity with the microorganisms or enzymes to be used. Such reaction activity is a main economical factor of industrial production.
2. Prior Art
Processes for hydrating nitrile compounds to produce the corresponding amide compounds by the action of microorganisms having enzymatic activity which hydrates a nitrile compound into the corresponding amide compound (i.e. nitrilase activity) are described in Japanese Patent Publication Nos. 17918/81 and 38118/81 and Japanese Laid-Open Patent Application (Kokai) No. 86186/76 Specifications. Microorganisms play an important role in these reactions, and several microorganisms are disclosed in the specifications referred to above.
3. Problems
It has been found by the present inventors that the nitrilase activity cannot be exhibited sufficiently when a large metal reaction apparatus is used in order to carry out hydration reaction of nitrile compounds in an industrial scale by utilizing the nitrilase activity of these microorganisms. It has been uncertain whether these phenomena are caused by the microorganisms themselves or the material and structure of the reaction apparatus or other reasons. Thus it was necessary to solve these problems for industrial operation of a microbiological process for producing amide compounds.